This invention relates to fire hydrants and, more particularly, to a valve assembly for the main valve of a fire hydrant which provides a supplemental seal for the main valve as well as a means for assembling a fire hydrant without damage to the valve apparatus.
Conventional fire hydrants typically include an elongated circuit having nozzle outlets thereon and projecting from the ground in which is mounted an elongated rod for operating a main valve to close off water from a supply line well below ground level. The main valve typically includes a sealing member bearing against a brass valve seat ring or other member threadedly secured within the barrel of the hydrant below ground level. A common and reoccurring problem with conventional hydrant structures is the failure of the sealing member and/or seat member from age, deterioration or the like necessitating replacement of the sealing member. In order to replace the member, it is necessary to unscrew the valve seat ring which in many cases has become corroded and extremely difficult to remove. Such corrosion results from exposure to water from normal hydrant usage and/or any leakage of water past conventional sealing points between the inside of the conduit of the hydrant and the valve seat ring.
Not only can water leak past the seal between the valve seat ring and conduit to cause corrosion of the valve seat ring as mentioned above, but failure or deterioration of either this seal or the main seal of the main sealing member against the valve seat ring causes the hydrant to fill with water above ground level. When this occurs in winter or freezing conditions, fracture or other damage to the hydrant could result. Consequently, both of the above-mentioned seals in a conventional fire hydrant must function to prevent such leakage and damage.
For replacement of the conventional seals as mentioned above, it is necessary that the hydrant be disassembled and then reassembled when in place in the ground. Because the valve seat ring is typically threaded into position and because the main sealing member must pass through a narrow, threaded portion of the hydrant conduit to allow the seat to be threaded into place, damage can occur to parts of the main valve when lowering the valve assembly into positon below ground level from above. Such damage can include galling or peeling of the sealing O-rings on the valve seat rings, stripping or gouging of the threads in the cast iron barrel or on the brass seat ring, and/or difficulty in obtaining proper seating of the sealing O-rings.
The present valve assembly provides a supplemental seal which cooperates with the other seals to ensure against and provide a solution for the above sealing problems as well as providing a means for guiding and facilitating the reassembly of a hydrant when replacement of the seals or other maintenance is necessary.